Hand-held vacuum cleaners of the foregoing dust-cup type have previously been provided, and have gained market acceptance, particularly smaller and lighter versions powered by rechargeable batteries carried within the unit. Earlier units had separate nozzle structure outside the upstream end of the dust cup, as in U.S. Pat. No. 3,513,500. Later units had a nozzle integrally formed within the upstream end of the dust cup, as in U.S. Pat. No. 4,209,875.
The advent of practical rechargeable batteries has led to their use as the power source for cleaners of this general type. Since the batteries are exhausted after several minutes of use, it is desirable to maintain them on constant charge during storage of the cleaner. In an effort to accomplish this conveniently, cleaners have been provided with means for automatically connecting and disconnecting the cleaner from a charger as the cleaner is stored or removed from storage for use, as for example in U.S. Pat. No. 4,225,814. However, such store-and-charge means has been rather bulky and ungainly. Also, when wall-mounted for saving of space, such store-and-charge means has required the cleaner to be pointed downwardly, with the vacuum intake end supported on a small ledge. The undesirable result is that any small amounts of dirt trapped upstream of the flap as the cleaner is turned off, on successive uses and storing, tend to successively be deposited on the small ledge or to spill off the edge thereof. Furthermore, the cleaner has not been rechargeable independently of the mounting bracket forming the storage means and to which the charger is permanently connected.
The flap valve associated with the vacuum nozzle of cleaners of the dust-cup type should interfere minimally with airflow while still providing proper shutoff. Prior flap valves in such cleaners have extended substantially perpendicularly to the direction of airflow when in their shut-off position, thereby providing a relatively inefficient, power-consuming arrangement.
The intake mouth itself should be prevented from sealing against the surface being vacuumed by a suitable serration or comb, thereby assuring maintenance of air wattage at all attitudes of the cleaner, and this should be accomplished in a simple manner. Prior art devices of this type have generally failed to provide any such means, evidently because of the perceived difficulty of doing so in a manner that would be aesthetically acceptable and at the same time not unduly costly in respect of increased complications in forming the dust cup as a relatively thin-walled, molded plastic part--the manufacturing method of first choice.
Provision must be made for holding the open mouth of the replaceable filter bag in sealing relationship with the cleaner structure in the vicinity of the large downstream end or mouth of the dust cup when the cleaner is in assembled condition. In one early example of the prior art, seen in U.S. Pat. No. 4,011,624, a bracket was provided extending in front of the impeller intake of the cleaner proper and adapted to be gripped by an elastic bag mouth. In later examples of the prior art, the sealing relationship has been accomplished by providing the dust bag with a flange (as in U.S. Pat. No. 4,209,875) or an elastomeric ring (as in U.S. Pat. No. 3,513,500) designed to engage the mouth of the dust cup and thereby close off and mount the mouth of the dust bag. These relatively complicated arrangements have contributed to the cost and inconvenience of providing and using replacement bags.
Cleaners of this general type are provided with latch means for releasably holding the dust cup in position on the body of the cleaner. Latch means of the prior art have generally been exposed to build-up of dust within the dust cup, leading to a tendency to foul the latch and require it to be cleaned from time to time. Furthermore, the latch means should be easy and convenient to use for ease of cleaning out the dust cup. A power switch is also necessary, an both it and the latch means should be simple and economical to make and to assemble with the remainder of the cleaner. For saving manufacturing costs, it is particularly desirable that the latch be "forgiving" of variations in manufacturing tolerances and yet be easy and reliable in operation over a range of such tolerances.